We know current photographic sliding rails available on the market mainly includes pure manual mode, pure automatic mode, and manual plus automatic mode which can operate both manually or automatically. As to the pure manual mode sliding rail, a flywheel is probably needed to store energy to make sliding smoothly. As to the pure automatic mode, a motor driven by an inbuilt battery or an external mains supply is required to drive a sliding block to slide. As to the photographic sliding rail of the manual plus automatic mode, a specialized conversion structure is required to install a flywheel module and an electric module. At present, the photographic sliding rail of the manual plus automatic mode employs a transmission mode adopting a transmission belt such as leather belt or synchronous belt. When switching between the flywheel module and the electric module, it is needed to demount and mount many parts, which makes the demounting and mounting cumbersome and inconvenient when converting the transmission mode. In addition, belt transmission is liable to generate vibration during operation, thereby impacting the photographic effect. Moreover, the length of the transmission belt such as leather belt or synchronous belt is non-adjustable, it is troublesome and time-consuming when the photographic sliding rail needs to connect with or reduce one or more pieces of rails to increase or shorten the rail length so as to be carried conveniently and meet the photographic requirements, because it is needed to loosen screws first to take out original parts such as transmission belt, then connect rail(s) of desired length, and finally mount a new transmission belt and tighten the screws and so on. Therefore, the applicant makes an improvement to the photographic sliding rail of the manual plus automatic mode.